/*
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ 

package com.sqlcrypt.database;

/**
 * Hex encoder and decoder.
 * 
 * @since 1.1
 * @author Apache Software Foundation
 * @version $Id: Hex.java,v 1.13 2004/04/18 18:22:33 ggregory Exp $
 */
public class Hex {

    /** 
     * Used building output as Hex 
     */
    private static final char[] DIGITS = {
        '0', '1', '2', '3', '4', '5', '6', '7',
           '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
    };


    /**
     * Converts an array of bytes into an array of characters representing the hexidecimal values of each byte in order.
     * The returned array will be double the length of the passed array, as it takes two characters to represent any
     * given byte.
     * 
     * @param data
     *                  a byte[] to convert to Hex characters
     * @return A char[] containing hexidecimal characters
     */
    public static char[] encodeHex(byte[] data) {

        int l = data.length;

           char[] out = new char[l << 1];

           // two characters form the hex value.
           for (int i = 0, j = 0; i < l; i++) {
               out[j++] = DIGITS[(0xF0 & data[i]) >>> 4 ];
               out[j++] = DIGITS[ 0x0F & data[i] ];
           }

           return out;
    }
}

